2011 Particle Accelerator Conference - List of Authors (Saunders, J.)

Paper

Title

Page

Summary Report for the C50 Cryomodule Project

1044

M.A. Drury, G.K. Davis, J.F. Fischer, C. Grenoble, J. Hogan, L.K. King, K. Macha, J.D. Mammosser, C.E. Reece, A.V. Reilly, J. Saunders, H. Wang
JLAB, Newport News, Virginia, USA
E. Daly, J.P. Preble
ITER Organization, St. Paul lez Durance, France

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract DE-AC05-06OR23177.
The Thomas Jefferson National Accelerator Facility has recently completed the C50 cryomodule refurbishment project. The goal of this project was to enable robust 6 GeV, 5 pass operation of the Continuous Electron Beam Accelerator Facility (CEBAF). The scope of the project included removal, refurbishment and reinstallation of ten CEBAF cryomodules at a rate of three per year. The refurbishment process included reprocessing of SRF cavities to eliminate field emission and to increase the nominal gradient from the original 5 MV/m to 12.5 MV/m. New “dogleg“ couplers were installed between the cavity and helium vessel flanges to intercept secondary electrons that produce arcing in the fundamental Power Coupler (FPC). Other changes included new ceramic RF windows for the air to vacuum interface of the FPC and improvements to the mechanical tuner. Damaged or worn components were replaced as well. All ten of the refurbished cryomodules are now installed in CEBAF and are currently operational. This paper will summarize the performance of the cryomodules. This paper will also look at problems that must be addressed by future refurbishment projects.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

THOCS3

R&D Status for In-Situ Plasma Surface Cleaning of SRF Cavities at Spallation Neutron Source

2124

S.-H. Kim, M.T. Crofford
ORNL, Oak Ridge, Tennessee, USA
M. Doleans
NSCL, East Lansing, Michigan, USA
J.D. Mammosser
JLAB, Newport News, Virginia, USA
J. Saunders
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
The SNS SCL is reliably operating at 0.93 GeV output energy with an energy reserve of 10MeV with high availability. Most of the cavities exhibit field emission, which directly or indirectly (through heating of end groups) limits the gradients achievable in the high beta cavities in normal operation with the beam. One of the field emission sources would be surface contaminations during surface processing for which mild surface cleaning, if any, will help in reducing field emission. An R&D effort is in progress to develop in-situ surface processing for the cryomodules in the tunnel without disassembly. As the first attempt, in-situ plasma processing has been applied to the CM12 in the SNS SRF facility after the repair work with a promising result. This paper will report the R&D status of plasma processing in the SNS.

Slides THOCS3 [3.294 MB]

Paper	Title	Page
TUP108	Summary Report for the C50 Cryomodule Project	1044
	M.A. Drury, G.K. Davis, J.F. Fischer, C. Grenoble, J. Hogan, L.K. King, K. Macha, J.D. Mammosser, C.E. Reece, A.V. Reilly, J. Saunders, H. Wang JLAB, Newport News, Virginia, USA E. Daly, J.P. Preble ITER Organization, St. Paul lez Durance, France
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract DE-AC05-06OR23177. The Thomas Jefferson National Accelerator Facility has recently completed the C50 cryomodule refurbishment project. The goal of this project was to enable robust 6 GeV, 5 pass operation of the Continuous Electron Beam Accelerator Facility (CEBAF). The scope of the project included removal, refurbishment and reinstallation of ten CEBAF cryomodules at a rate of three per year. The refurbishment process included reprocessing of SRF cavities to eliminate field emission and to increase the nominal gradient from the original 5 MV/m to 12.5 MV/m. New “dogleg“ couplers were installed between the cavity and helium vessel flanges to intercept secondary electrons that produce arcing in the fundamental Power Coupler (FPC). Other changes included new ceramic RF windows for the air to vacuum interface of the FPC and improvements to the mechanical tuner. Damaged or worn components were replaced as well. All ten of the refurbished cryomodules are now installed in CEBAF and are currently operational. This paper will summarize the performance of the cryomodules. This paper will also look at problems that must be addressed by future refurbishment projects. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

THOCS3	R&D Status for In-Situ Plasma Surface Cleaning of SRF Cavities at Spallation Neutron Source	2124
	S.-H. Kim, M.T. Crofford ORNL, Oak Ridge, Tennessee, USA M. Doleans NSCL, East Lansing, Michigan, USA J.D. Mammosser JLAB, Newport News, Virginia, USA J. Saunders ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. The SNS SCL is reliably operating at 0.93 GeV output energy with an energy reserve of 10MeV with high availability. Most of the cavities exhibit field emission, which directly or indirectly (through heating of end groups) limits the gradients achievable in the high beta cavities in normal operation with the beam. One of the field emission sources would be surface contaminations during surface processing for which mild surface cleaning, if any, will help in reducing field emission. An R&D effort is in progress to develop in-situ surface processing for the cryomodules in the tunnel without disassembly. As the first attempt, in-situ plasma processing has been applied to the CM12 in the SNS SRF facility after the repair work with a promising result. This paper will report the R&D status of plasma processing in the SNS.
	Slides THOCS3 [3.294 MB]